Method and apparatus for collecting chemicals from semiconductor wafer
An apparatus and a method are provided for accurately analyzing and evaluating a degree of contamination on a chamfered part without mixing impurities from parts other than the chamfered part into chemicals. At a position in which, on a front plane flat part of a semiconductor wafer, a boundary region bordering the chamfered part can come into contact with the chemicals, a radius direction position of the chemicals (a distance between a chemicals center and a wafer center) is determined, scanning is performed in a circumference direction, and the chemicals including impurities are collected. Then, at a position that can be brought into contact with the both chamfered part of the semiconductor wafer and the boundary region, a radius direction position of the chemicals is determined, scanning is performed in the circumference direction and the chemicals including impurities are collected. A liquid drop holder is, for instance, relatively rotated in the circumference direction from a desired start point on the circumference of the semiconductor wafer to a finish point.
1. A method of collecting impurities from a semiconductor wafer, in which impurities are removed from the wafer's surface by moving a liquid drop relative to the surface of the wafer so as to dissolve impurities into the liquid drop, the method comprising;
forming a liquid drop on the surface of the wafer;
holding the liquid drop with a liquid drop holder that can move the drop across the surface of the wafer;
a first scanning step of scanning in the circumference direction while causing the drop to move radially from the center of the wafer to, on a front plane flat part of the semiconductor wafer, a boundary region bordering a chamfered part;
a second scanning step of fixing the drop at a radial position where the drop can contact the boundary region bordering the chamfered part, and scanning in the circumference direction;
a first collecting step of collecting the drop that includes dissolved impurities that were removed from the front plane flat part of the semiconductor wafer;
a third scanning step of positioning the liquid drop holder at a position where a drop held by the drop holder can contact both the chamfered part and boundary region of the semiconductor wafer, fixing the held drop at the radial position where the drop can contact both the chamfered part and the boundary region, and scanning in the circumference direction so that impurities on the chamfered part can be dissolved into the held drop; and
a second collecting step of collecting the drop that includes impurities that were removed from the chamfered part of the semiconductor wafer, said second collecting step being separate from said first collecting step.